Author:

Abstract:

Neuropeptide Y (NPY) plays an important role in the regulation of basic physiological functions, including cognitive function associated with learning and memory [Flood et al., Brain Res., 503: 73-82, 1989]. In the present study, the effect of over expression of NPY in the brain of aged transgenic rats [Michalkiewicz et al., Methods Mol Biol.;153:73-89, 2000] on spatial learning in the delayed alternation version of the Morris Water Maze task (target platform alternating between two locations) was investigated. For five consecutive days, the rats were submitted to six trials with a cut-off time of 60 s and an average intertrial interval of 15 min. The over expression of NPY did not significantly influence the ability of the animals to locate the hidden platform throughout the training. Both transgenic and control group showed a significant improvement per trial as well as per day. The visual cued test revealed no visual impairments, and no non-specific deficits in motor behaviour or change in exploratory behaviour occurred in both groups. However, the escape latency for transgenic rats was significantly shorter in comparison with the control rats during the visual cued test (p<0.05). This observation is somewhat unexpected, since in a separate group of NPY over expressing rats evaluated in the plus maze test, anxiolytic activity clearly was observed in transgenic rats, in accordance with earlier data [Thorsell et al., PNAS 7;97(23):12852-7, 2000]. We are currently using molecular approaches such as proteomics to clarify the mechanisms involved in these various behaviours.